Elevator door cycling control

ABSTRACT

An elevator system including an elevator car mounted in a building to serve the floors therein. A car monitor is provided which is responsive to the operation of the car when it is stopped at a floor. The occurrence of an unusual condition which results in unnecessary cycling of the doors between their open and closed positions, results in corrective action being taken by the car monitor to stop the door cycling and to enable the car to leave the floor.

United States Patent Booker, Jr.

[ ELEVATOR DOOR CYCLING CONTROL [75] inventor: Clyde A. Booker, Jr., Pittsburgh, Pa. :Zjg iz fiysgr i g fifi3 :23:? [73] Assignee: Westinghouse Electric Corporation, Attorney, Agent, or Firm-D. R. Lacke y Pittsburgh, Pa. v

[22] Filed: Apr. 9, 1973 [57] ABSTRACT [211 App]. No.: 349,524 An elevator system including an elevator car mounted in a building to serve the floors therein. A car monitor is provided which is responsive to the operation of the CCll Car when is Stopped at a floor. The Occurrence of an [58] 34 35 29 unusual condition which results in unnecessary cycling care of the doors between their open and closed positions, 7 results in corrective action being taken by the car [56] References cued monitor to stop the door cycling and to enable the car UNITED STATES PATENTS to leave the flow 2.835346 5/I95s Burgy 187/29 R v 3,513,945 5/1970 Hall et al. 187/29 R7 12 Clfllms, 4 Drawmg Figures TIMIANG 3 TlMllNG I cog 1230a P $2 sgmg me CARS QTOR {l5 4 rI-IIIve 22 v INTERFACE fl HMING CAR 56 3a M0 T R [I 30m LANDING l UNIT I ggalait swIrcHes I V HATCHWAY 44 52 TIMING-1 .32 83g; op g i on "iszik n LAII i'IEiI'Ns i 2nd LANDING PER R I 54 w FEED 5i APJSRER 'l g gggsg 333%? E1.- 48 -1 124 I 55 let LANDING PULSE b 11 I -25 PATENTEDJIIII 4 IIIII N 3 42 4 SHEET 1 BF 3 TIMING l 4 TIMING {II OORRIOOR REMAINING CARS cALL SYSTEM H I CONTROL PROcEssOR OF BANK GA 26 I8 "93 I uiMOToR 3O L I [I5 22 4 INTERFACE ,70 4 TIMING CAR IE- IBIa'OIh LANDING I TOR I I CAR CALI- SWITCHES I 60 62 CONTROL IN L y HATCHWAY 52 TIMING 34 E o I 1 f "36' E T0 DOOR FLOOR HALL I256 888 OPERATOR SELECTOR LANTERNs V v 2nd LANDING OPERATOR 1 L54 r I I I 8 MOTOR -SPEED NDISTANCE I CONTROLLER" PATTERN PULSES 4o GENERATOR 24 FIGI 56 Is? LANDING L PULSE w 11 DETECTOR\ 64 I 2e 32% U SE OE TE OTOR COMPARATOR gg DORR To INTERPA E l5 UPFTZRDWK FIG. 2 DO UCX,D x" mm OALL DCE,UCE,NCI SELEC OR UPRZ'DNRZ A CAR LOGIC 22 MONITOR gg' I L70 DCLA O0RRA,ucx"A' ,O' cx A T SYNCHRONIZER ,when

1 ELEVATOR DOOR CYCLING CONTROL BACKGROUND OF THE INVENTION lyField of the Invention The invention relates in general to elevator systems,

and more specifically to control apparatus for elevator systems.

2. Description of the Prior Art When an elevator car stops at a floor, such as in response to a flooror car call, the call is cancelled, and the doors of the car and hatch open to allow passengers to leave and prospective passengers to enter the car. 7

the normal door open time, i.e., noninterference time, expires, the door closing operation is initiated. If the control which initiated the door open request receives another'signal, such as due to a floor call from the floor at which the car is located, and the car is not busy, the doors will reopen to allow the prospective passengers to enter. If the call from the flogr at which the car is located is due to a continuously maintained call signal, due to a malfunction in the floor call circuits, the door open request will be reinitiated each time the non-interference time expires and the door open 'request is reset. Thus a continuously maintained call for elevator service for the floor at which the car is located will result in the doors opening and closing and repeating this cycle endlessly until the malfunction either clears itself or the car is taken out of service and maintenance personnel correct the source of the problem. Endless cycling of the doors between their open and closed positions causes unnecessary wear on the door operator, as well as effectivelyremoving the elevator car from useful service.

A prior art approach to t he problem is to modify each 7 call push button circuit such that a call will be-regissuMMA Y OF THE INVENTION leave the floor to serve the other calls. Continuously registered up or downfloor calls are selectively forced to be reset, allowing the elevator car to handle calls for a predetermined service direction from a floor venthoyshth sircui ry 9! this o r s Continuously providing a call for elevator service in the opposite direction.

In an elevator system having a plurality of cars controlled by a system processor, which system processor makes specific assignments to cars which are not busy but which are standing at a floor with their doors closed, the invention provides control for indicating to the availability apparatus associated with the car that the doors are closed when they are in fact being held open by the control apparatus to prevent them from cycling. Thus, the corrective action taken to prevent door cycling does not prevent cars from being considered by I the system processor for assignment to a specific task.

BRIEF DESCRIPTION OF THE DRAWING The invention may be better understood, and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of exemplary embodiments, taken with the accompany drawings, in which:

FIG. 1 is a block diagram of an elevator system constructed according to the teachings of the invention;

FIG. 2 is a block diagram which illustrates the relationship between the floor selector of the elevator systern of FIG. 1 and a car monitor function constructed according to the teachings of the invention;

FIG. 3 is a schematic diagram of car monitor appara I I tus which may be used for the car monitor function Briefly, the present invention is anew and improved elevator system which prevents unnecessary cycling of the doors of an elevator car due to a malfunction by employing control apparatus which counts door open requests when a car is at a floor. When a predetermined number of door open requests are detected or counted, the control apparatus takes corrective action to prevent the doors from. cycling. If the plural door open requests are due to a continuously maintained up or down floor call from the floor of the car position, the control apparatus forces a reset for the call and inhibits the call from being considered by the call selector and door open request function, permitting the car to be come available to serve other calls. ln a preferred embodiment, the doors of the car are forced to remain in their open state, if there are no calls for elevator service, so the car may beenteredlf there are calls for 'servicein the elevator system, the doors are not forced to any positibnThe resetting of the call andinhibiting it from affecting the call selector and door open request functions. automatically allows the elevator car to shown in block form FIGS. land 2; and FIG. 4 is a schematic diagram which illustrates a modification of the car monitor apparatus shown in FIG. 3. I

Referring now to the drawings, and FIG. 1 in particular, there is shown a block diagram of an elevator system 10 which incorporates a car monitor function in accordance with the teachings of the invention. Elevator system 10 includes an elevator car 12, the movement of which may be controlled by a system processor llQSince each car of a bank of cars, and the controls therefor, would be similar in construction and operation, only the controls for a single car 12 are illustrated and described.

More specifically, car 12 is mounted in a hatchway 13 for movement relative to a structure 14 having a plurality of landings, such as 30, with only the firstsec- 0nd and thirtieth landings being shown in order to simplify the drawings. The car 12 is supported by a rope 16 which is reeved over a traction sheave 18 mounted on the shaft of a drive motor 20, such as a direct current motor as used in the Ward-Leonard drive system, or in' a solid state drive system. A counterweight 22 is connected to the other end of the rope 16.. A governor rope 24 which is connected to, the top and bottom of the car is reeved-over a governor sheave 26 located above the highest point of travel of the car in the hatchway 13, and over a pulley 28 located at the bottom of the hatchway. A pick-up 30 is disposed to detect movement of thecar 12'through the effect of circumferen- :tially spaced openings 26a in the governor sheave The openings in the governor sheave are spaced to provide a pulse for each standard increment of travel of the car, such as a pulse for each 0.5 inch of car travel. pick-up 30, which may be of any suitable type, such as optical or magnetic. provides pulses in response to the movement of the openings of 26a in the governor sheavepick-up 30 is connected to a pulse detector 32 which provides distance pulses for a floor selector 34.

Car calls, as registered by push button array 36 mounted in the car 12, are recorded and serialized in car call control 38, and the resulting serialized car call information is directed to the floor selector 34.

Corridor or floor calls,as registered by push buttons mounted in the corridors, such as the up push button 40 located at the first landing, the down push button 42 located at the thirtieth landing, and the up and down push buttons 44 located at the .second and other intermediate landings, are recorded and serialized in corridor call control 46. The resulting serialized corridor call information isdirectedto the system processor 11. A system processor 11 directs the corridor calls to the cars through an interface circuit, shown generally at 15, to effect efficient service for the various floors of the building and effective use of the elevator cars.

The floor selector 34 processes the distance pulses from the pulse detector 32 to develop information concerning the position of the car 12 in the hatchway l3, and also directs these distance pulses to a speed pattern generator 48 which generates a speed reference signal for a motor controller 50, which in turn provides the drive voltage for motor 20.

The floor selector 34 keeps track of the car 12 and the calls for service for the car, it provides the request floor selector 34 also provides signals for controlling such auxiliary devices as the door operator 52, the hall lanterns 54, and it controls the resetting of the car call and corridor call controls when a car or corridor call has been serviced.

Floor selector 34 also provides signals for the car monitor 70, which in turn provides signals for the floor selector 34 and interface 15. The car monitor detects abnormal operation of the car, such as in response to a malfunction which continuously registers a call at a floor. even after the elevator car has arrived at the floor, and takes corrective action to prevent unnecessary wear of mechanical equipment, such as the door operator, and to inhibit the false" call from having any effect on the control system to enable the car at the floor of this continuously registered call to leave the floor in response to other callsin the building, or in response to assignments given to the carby the system processor.

Landing, and leveling of the car at the landing, is accomplished by a hatch transducer system which utilizes inductor plates 56 disposed at each landing, and a transformer 58 disposed on the car 12.

The motor controller 50 includes a speed regulator responsive to the reference pattern provided by the speed pattern generator 48. The speed control may be derived from a comparison of the actual speed of the motor and that called for by the reference pattern by using a drag magnet regulator, such as disclosed in US. Pat. Nos. 2,874,806 and 3,207,265, which are assigned to the same assignee as the present application. The precision landing system using inductor plates and transformer 58 is described in detail in US. Pat. No. 3,207,265.

An over speed condition near either the upper or lower terminal is detected by the combination of a pick-up 60 and slow-down blades, such as a slow-down blade 62. The pickup 60 is preferably mounted on the car 12, and a slow-down blade is mounted near each terminal. A slow-down blade has spaced openings, such as a toothed edge, with the teeth being spaced to generate pules in the pick-up 60 when there is relative motion between them. These pules are processed in pulse detector 64 and directed to the speed pattern generator 48 where they are used to detect an overspeed condition.

A new and improved floor selector 34 for operating a single elevator car, without regard to the operation of the car in a bank of cars, has been disclosed in application Ser. No. 254,007. filed May 17. 1972. now US. Patent 3,750,850, which is assigned to the same assignee as the present application. Modification of the floor selector 32 to adapt it to bank operation and 209152.9ras2mt99se1t1 .issi s sissqin,app tion Ser. No. 340.618 filed Mar. 12. 1973 in the name of D. Edison, which application is assigned to the same assignee 'as the present application. In order to avoid duplication and to limit the com plexity of the present application. both of these applications are hereby incorporated by reference, and they will hereinafter be referred to as the first and second incorporated applications, respectively.

With the floor selector disclosed in these incorporated applications the elevator car only sees" a call at the floor of the car when the first scan signal FSC goes low (true) at'the start of a run. Thus, a corridor call which is continuously registered due to some malfunction will cause door cycling only when there are no other calls in the system. The car monitor of the invention may be used, however, with floor selectors which have no restriction on the cars ability to see a call at the floor of the car.

FIG. 2

FIG. 2 is a block diagram which illustrates the functions of the floor selector 34 which provide signals for the car monitor function 70. Certain of these signals are output by the car monitor function back to the floor selector 34, or the interface 15, where the output signals from the car monitor 70 which are similar to the input signals, except subject to malfunction, being given the same reference letters followed by the letter A, to indicate the fact that the signal may be modified by the monitor 70.

More specifically, the functions of floor selector 34 which provide signals for car monitor 70 are the comparator 82, the call selector 92', synchronizer 94, and logic 96', which are shown and described in detail in the first and second incorporated applications. it will be sufficient for purposes of this application to describe the nature of the signals provided by these functions. These incorporated applications handle calls for elevator service serially, placing them in predetermined time or scan slotsassociated with the floors of the calls, and the car monitor function 70 will be described with this serial system. However, it will be apparent that the inventive concept is equally valid in an elevator system which handles calls on a parallel basis.

The Comparator 82 provides a signal EQlZ which represents the floor of the advanced car position of the elevator. When the car isstopped at a floor, the advanced car position is the actual floor location of the car, and when the car is moving the advanced car position is the closest floor at which the car may make a normal stop according to a predetermined deceleration schedule. Since the elevator system is a serial system, the signal EOlZ appears in the time or scan slot associated with the floor of the advanced car position.

The call selector 92' provides the door open request signal DOR which is low or true w h en the call selector 92' requires that the car doors open. For example, when the car is enabled for up floor calls, an up floor call from a floor will cause the door open request signal DOR to become true when the advanced car position of the car is the same as that of the call floor. In like manner, the door open request signal will be initiated in response to adown floor call, a car call, and a call at the floor of the car. i

Call selector 92 also provides serial up and down floor call signals UCX and DCX, respectively, which contain up and down floor calls in the time slots associated with the floors of the calls, and up and down .floor call reset signals UPRZ and DNRZ, respectively,

Synchronizer 94 provides a signal PCR which goes low ortrue eachtime the advanced car position of the elevator car changes floors.

Logic 96 provides the up call enable and down call enable signals UCE and DCE, respectively. The up call enable signal UCE is true when the elevator car is set for up service and up travel and is not bypassing floor calls. The down call enable signal DCE is true when the elevator car is set for down service'and down travel and thecar is not'bypassing floor cal-ls.' Logic 96' provides signal NCL which is true when thereare no floor calls and no car callsin the system.

The door monitor 70 also receives door related signals DCL and DORR. Signal DCL goes true when the car doors close, such as indicated by a suitably located limit switch. Signal DORR goes true when the car is at a'floor with its doors open and the non-interference time expires. J r

The car monitor 70 provides signals DORRA, UCXA and DCXA for call selector 92, signal DCLA for logic 96, and signals UPRZA and DNRZA for interface 15. When the operation of the elevator car while it is standing at a floor is normal, as detected by the car monitor function 70, the output signals from monitor 70 will be at the same logic level as the input signals having the same descriptive letters except for the'letter on the end of the signal letter. Thus, the car monitor function 70 has no circuit effect during normal operation of the elevator car.

The car monitor 70 is responsive to the door request signal DOR. Each time signal DOR goes low or true while the elevator car is at any one floor, it is counted. In a preferred embodiment of the invention, if signal first counter, and if signal DCE is true the occurrences of DOR are counted on a second counter. When either counter, if two are used, or the counter, if only one is used, reaches a predetermined count, such as three, and there are no corridor or car calls (NCL 1), the reset signal DORRA isforced high, preventing a low reset signal DORR from closing the doors of the elevator car. Thus, cycling of the doors is prevented. Preventing door cycling by forcing them to stay open when there are no calls in the system is preferable to forcing them to their closed position, since it allows prospective passengers at the floor to leave the floor if the malfunction is due to a continuously registered floor call, by entering the car and registering a car call.

The car is permitted to leave the floor if the malfunction is a continuously registered call by removing an up or down call from this floor from the up or down serial call streams UCX and DCX, which signals are referred to as UCXA and DCXA after passing through the monitor function 70, and by forcing the resetting of the up or down floor call via signals UPRZA or DNRZA, re spectively, which reset signals are directed to the interface 15. Thus, a floor call for this floor of the car is reset or indicated answered, and the call is prevented from reinitiating the functions of the call selector circuit 92 by removing the call from the serial call stream prior to its being applied to the various functions of the call selector 92. The function of removing the call from the call stream is performed, for example, before the call stream is applied to the call selector memories or flip-flops,with signals UCXA and DCXA entering inverters 254 and 264 of the call selector 92 shown in FIG. 15 of the second incorporated application.

The system processor 11 assigns elevator cars which are available for assignment, i.e., not already busy serving a call for elevator service, to certain calls, or to park at predetermined floors. The logic function 96 makes a determination of car availability for use by the system processor 11 by checking to see if the car is moving, checking to see if any calls are being considered by the floor selector and checking the position of the car doors. When the car is parked at a landing with its doors closed and the floor selector can see no calls for elevator service, the'car is determined by logic 96' to be available according to the selector, and the signal AVAS is sent to the system processor. When the car monitor function forces the car doors to their open position when the car monitor function performs it corrective action at a time when the floor selector can see no calls in the elevator system, the signal DCL will indicate that the doors are open and thelogic 96' function would ordinarily indicateto the system processor 11 that the car is not available for assignment. However, the present invention teaches directing the signal DCL to the car monitor function 70 before it is applied to logic 96'. When the car monitor function 70 forces the doors to remain'in their open position while there are no calls being considered by the floor selector the sig- FIG. 3

FIG. 3 is a schematic diagram of car monitor 70 constructed according'to a specific embodiment of the in vention. In this embodiment of the invention, a first counter 100 is provided for counting door open requests when the car is enabled for up calls, and a second counter 102 is provided for counting door open requests when the car is enabled for down calls. Two counters are preferred, one for each service direction, since a car enabled for one service direction may have its service direction changed while it is at a floor. A counter for each service direction thus insures that the full predetermined count will be applied to a specific service direction before it reaches its predetermined count or limit and initiates corrective action. A'single counter, however, may be used, and an embodiment of the invention which utilizes a single counter is shown in FIG. 4.

Counter 100 may include first and second D-type edge triggered flip-flops 104 and 106, respectively, such as Texas lnstruments SN7474, and counter 102 may include similar flip-flops 108 and 110. Counter 100 is responsive to door open requests when the car is enabled for up calls by connecting the up call enable signal UCE to one input of a twoinput AND gate 112, and the door open request signal DOR to the other the serial advanced car position signal EQlZ. When the counter 100 reaches a count of three, the output of NAND gate 118 goes low during the scan slot associated with the floor at which the elevator car is standing. The output of NAND gate 118 is connected to an input ofa two input NAND gate 126 which has its other input connected to receive the serial up floor call stream UCX via inverter 128. When counter 100 has not reached its predetermined count, the up call stream proceeds from the call selector 92 through monitor 70 and back to the call selector 92' without modification. When counter 100 counts out, i.e., to the count of three in this example, it inhibits NAND gate 126 for the floor at which the car is standing, forcing the output of NAND gate 126 high during this scan slot to signify no up call, regardless of the signal level of signal UCX for this scan slot. Thus, signal UCXA will not contain an up call for the floor of the car, and if a continuously maintained up call signal was the cause of the door cycling, this call will not be re-registered in the call selector 92' following reset of the call.

Forcibly resetting a continuously maintained call is accomplished by NAND gate 120. NAND gate 120 has input via an inverter or NOT gate 114. The output of AND gate 112 is connected to the C inputs of flip-flops 104 and 106. The Q output of flip-flop 104 is connected to the D input of flip-flop 106, and the Q output of flip-flop 106 is connected to the D input of flip-flop 104. The Q and Q outputs of flip-flops 104 and 106, respectively, are the outputs of the counter, signifying three discrete door open request signals DOR when these outputs are both at the logic one level. if it is desired to have a different number of door open requests initiate corrective action of the monitor 70, the flipflops 104 and 106 would be connected, and predetermined terminals thereof used as outputs, according to the specific count required.

Signal PCR is connected to the CLR inputs of the flip-flops of the counters, with a low or true PCR signal, which is true when the car moves to anotherfloor, starting the counter 100 with the logic level signals indicated in FIG. 3, with the Q outputs at logic zero and the Q outputs at logic one. Thus the outputs Q and Q of flip-flops 104 and 106', respectively, start at logic one and logic zero, respectively. The first true DOR signal, when the elevator car is enabled for up calls sets these two outputs at logic zero and logic zero, respectively, the second true DOR signal at the same floor sets these two outputs at logic zero and logic one, respectively, and, the third true DOR signal sets them both at the logic one level.

In like manner, counter 102 counts true door open request signals DOR when the elevator car is enabled for down calls via an AND gate 116 which has an input connected to the output of inverter 114 and an input connected to receive the down call enable signal DCE.

The output of counter 100 is monitored by NAND gates 118 and 120, and the output of counter 102 is monitored by'NAND gates 122 and 124. NAND gate 118 has three inputs, two of which are connected to the Q and Q outputs of flip-flops 104 and 106 of counter 100, and the remaining'input is connected to receive two inputs, connected to monitor the count of counter 100. The output of NAND gate is connected to one input of a two input NAND gate via an inverter 132, and theother input of NAND gate 132 is connected to receive signal EQlZ. Thus, when the counter 100 counts out, NAND gate 130 will output a logic zero during the scan slot associated with the floor at which the car is located. The output of NAND gate 130 is connected to one input of a two input NAND gate 134, and the other input of NAND gate 134 is connected to receive the up call reset signal UPRZ. The output of NAND gate 134 is connected to output terminal UPRZA via inverter 136. Thus, a true reset signal UPRZ will provide a true signal UPRZA, and when counter 100 counts to three, signal UPRZA will be forced true for the scan slot associated with the floor of the car. Thus, an up call for the floor of the call is reset, and if the call is a continuously registered call for some reason, it will be screened from the signal UCX, with the screened signal UCXA being used for the decision making functions of call selector 92'.

in like manner, NAND gate 122, along with a NAND gate 138, remove down calls from the serial call stream DCX when counter 102 reaches its preset count, and NAND gate 124, along with NAND gates and 142, and inverters 144 and 146, force a reset for a down call at the floor of the car.

if there are other calls for elevator service in the elevator system, and the door cycling was the result of a continuously registered up or down floor call, the car monitor 70 resets the call and prevents it from being reconsidered by the call selector 92. Thus, the car doors are permitted to close and the car is free to leave the floor to serve the other calls in the system.

If there are no calls for service in the elevator system and the car doors are held open by the car monitor 70, the car may still be made available for assignment by the system processor 11, despite the fact the doors are being held open. These functions are provided by NAND gates 150, 152, 154 and 156. NAND gate has its inputs connected to the outputs of NAND gates 120 and 124. When neither counter 100 nor counter 102 has counted to its preset number, the output of NAND gate 150 is at the zero logic level. If either counter reaches its preset count, the output of NAND gate 150 goes high. The output of NAND gate 150 is connected to an input of NAND gate 152. The other input of NAND gate 152 is connected to receive signal NCL, which is high or true when the car has no car calls and can see no floor calls. Thus, if neither counter has reached three,or if a counter has reached three and the car has a car call or can see a floor call the output of NAND gate 152 will be at the logic one level. If either counter reaches three and the floor selector can see no calls in the system, the output of NAND gate 152 goes to the logic zero level. The output of NAND gate 152 is connected to'inputs of NAND gates 154 and 156. NAND gate 154 has an input connected to receive the reset signal DORR which resets the flipflop which generated the door open request signal DORv When reset signal DORR goes true at the end of the noninterference time, the elevator car doors will reclose. Signal DORR, however, is passed through NAND gate 154 before it is used as a reset signal, and if the output of NAND gate 152 is zero, indicating a counter has reached its preset count with no calls above or below the position of the car, the output of NAND gate 154 is forced to the logic one level. Thus, the reset signal DORR is blocked from becoming true at output terminal DORRA, holding the car doors open until a call appears in the floor selector, which forces NCL low, or they caris otherwise given an assignment bythe system processor 11.

The car is allowed to become available in logic 96' by sending the door closed signal DCL to logic 96' via N AND gate 156 in monitor 70. Signal DCLA is applied to input terminal DCL of logic 96'. If either counter reaches its preset count and signal NCL is true, signal DCLA is forced high, indicating that the doors are closed, even though the doors of the car are held open by holding reset signal DORRA high.

FIG. 4

FIG. 4 is a schematic diagram of a car monitor function 70', which is similar tothe car monitor function 70 shown in FlG. 3, except a single counter is used. Like reference numerals in'FIGS. 3 and 4 indicate like components. i

In general, the schematic diagram shown in FIG. 4 is similar to that shown in FIG. 3, except AND gates 112 and 116, and counter 102, are eliminated. Instead of connecting the up call enable signal UCE to enable a specific counter, it is now connected to enable NAND gates 118 and 120. Instead of connecting the down call enable signal DCE to enable a specific counter, it is not connected to enable'NAND gates 122 and 124. The remaining portion of FIG. 4 is similar to that of FIG. 3, with the operation of the circuit shown in FIG. 4 being similar to that hereinbefore described relative to FIG. 3.

In summary, there has been disclosed a new and improved elevator system which takes corrective action to prevent unnecessary cycling of the doors of the elevator carbetween its open and closed positions. The corrective action taken by the invention enables the elevator car to serve other calls for elevator service, or to hold the car doors in the open position and make the car available for assignment if the car has no car calls and the floor selector can see no corridor calls. Thus, unnecessary wear of the door operator is prevented, and a malfunction in a call circuit which continuously maintains a false call for elevator service does not take an elevator car out of service but permits it to leave the floor of the continuously maintained call, to serve other calls for elevator service, or permits the car to become available for assignment to specific tasks by a system processor.

I claim as my invention: 1. An elevator system, comprising:

an elevator car having a door operable between open and closed positions, means for moving and stopping the elevator car at predetermined locations, first control means for providing a door. open request signal which initiates the opening of the car door in response to predetermined conditions, reset means providing a reset signal to initiate the closing of the car door in response to predetermined conditions, counting means counting the number of door open request signals initiated when the car is at any one of the predetermined locations, said counting means providing a limit signal when a predetermined number of door open requests is reached, and second control means responsive to the limit signal provided by said counting means to prevent the car door from cycling between its open and closed positions. 1 2. The elevator system of claim 1 wherein the predetermined locationsare floors of a building, and includ- 0 ing:

=call means for registering calls for elevator service i from the floors of the building served by the e|evator car, car position means providing a car position signal in dicative of the closest floor at which the car may I. make a normal stop when moving and the floor of the car when it is stopped, wherein the first control means provides a door open request signal in response to a call for elevator service from the floor of the car position signal, and wherein the second control means, in response to the signal provided by the counting means,

forces a reset of a call registered from the floor of the car and inhibits a call from the floor provided by said call means from affecting the firstcontrol means.

3. The elevator system of claim 2 wherein the call means provides requests for elevatorservice in both the up and down directions, and the second control means forces 'a reset and inhibits-the call for service from the means is responsive to said first and second signals to I reset and inhibit a call at the floor of the car requesting service in the up and down directions, respectively.

5. The elevator system of claim 1 including call means for registering calls for elevator service, call detector means which is in a first state when it can detect no calls above or below the position of the car and in a second state when it can, with the second control means including means responsive to the limit signal provided by the counting means when said call detector means is in its' first state to prevent the reset means from initiating the reset signal for closing the door of the elevator car.

6. The elevator system of claim including availability means for providing an available signal when the call detector can detect no calls for elevator service and the door of the elevator car is closed, and said second control means includes means for providing a signal for the availability means indicating that the car door is closed when the car door is open due to the second control means preventing the door from closing by preventing the reset means from initiating the reset signal.

7. An elevator system, comprising: a building having a plurality of floors, an elevator car mounted for movement in'said building to serve at least certain of the floors thereof, said elevator car having a door operable between open and closed positions to enable movement of load between the elevator car and floors of the building, first means for moving the elevator car relative to the floors of said building and to stop the elevator car at selected floors thereof, second means for pr oviding'a door open request signal which initiates the opening of the car door in response to predetermined conditions, third means providing a reset signal to initiate the closing of the car door after it has been open a predetermined period of time, fourth means counting the number of door open request signals initiated when the car is at a floor of the building, and providing a signal when a prede termined number of door open requests is reached,

and fifth means responsive to the signal provided by said fourth means to prevent the car door from cycling between its open and closed positions.

8. The elevator system of claim 7 including:

call means for registering calls for elevator service from the floors of the building served by the elevator car,

car position means providing a car position signalin- 45 initiating the reset dicative of the closest floor at which the car may make a normal stop when moving. and the floor of the car when it is stopped,

wherein the second means provides a door open request signal in response to a call for elevator service from the floor of the car position signal,

and wherein the fifth means, in response to the signal provided by the fourth means, forces a reset of a call registered from thefloor of the car and inhibits a call from the floor provided by said call means from affecting the second means.

9. The elevator system of claim 8 wherein the call means provides requests for elevator service in both the up and down directions, and the fifth means forces a reset and inhibits the call for service from the floor of the car only for a call having the same service direction as that being served by the elevator car.

10. The elevator system of claim 9 wherein the fourth means includes first and second counting means for counting door open requests when the car is serving calls for service in the up and down directions. respectively, the fourth means provides first and second signals when the first and second counters reach a predetermined count, respectively, and the fifth means is responsive to said first and second signals to reset and inhibit a call at the floor of the car requesting service in the up and down directions, respectively.

11. The elevator system of claim 7 including call means for registering calls for elevator service, sixth means which is in a first state when it can detect no calls above or below the position of the car and in a second state when it can, with the fifth means including means responsive to the signal provided by the fourth means when said sixth means is in its first state to prevent the third means from initiating the reset signal for closing the door of the elevator car.

12. The elevator system of claim 11 including availability means for providing an available signal when there are no calls for elevator service and the door of the elevator car is closed, and said fifth meansjncludes means for providing a signal for the availability means indicating that the car door is closed when the car door is open due to the fifth means preventing the door from closing by preventingthe third means from signal. 

1. An elevator system, comprising: an elevator car having a door operable between open and closed positions, means for moving and stopping the elevator car at predetermined locations, first control means for providing a door open request signal which initiates the opening of the car door in response to predetermined conditions, reset means providing a reset signal to initiate the closing of the car door in response to predetermined conditions, counting means counting the number of door open request signals initiated when the car is at any one of the predetermined locations, said counting means providing a limit signal when a predetermined number of door open requests is reached, and second control means responsive to the limit signal provided by said counting means to prevent the car door from cycling between its open and closed positions.
 2. The elevator system of claim 1 wherein the predetermined locations are floors of a building, and including: call means for registering calls for elevator service from the floors of the building served by the elevator car, car position means providing a car position signal indicative of the closest floor at which the car may make a normal stop when moving and the floor of the car when it is stopped, wherein the first control means provides a door open request signal in response to a call for elevator service from the floor of the car position signal, and wherein the second control means, in response to the signal provided by the counting means, forces a reset of a call registered from the floor of the car and inhibits a call from the floor provided by said call means from affecting the first control means.
 3. The elevator system of claim 2 wherein the call means provides requests for elevator service in both the up and down directions, and the second control means forces a reset and inhibits the call for service from the floor of the car only for a call having the same service direction as that being served by the elevator car.
 4. The elevator system of claim 3 wherein the counting means includes first and second counting means for counting door open requests when the car is serving calls for service in the up and down directions, respectively, the counting means provides first and second signals when the first and second counters reach a predetermined count, respectively, and the second control means is responsive to said first and second signals to reset and inhibit a call at the floor of the car requesting service in the up and down directions, respectively.
 5. The elevator system of claim 1 including call means for registering calls for elevator service, call detector means which is in a first state when it can detect no calls above or below the position of the car and in a second state when it can, with the second control means including means responsive to the limit signal provided by the counting means when said call detector means is in its first state to prevent the reset means from initiating the reset signal for closing the door of the elevator car.
 6. The elevator system of claim 5 including availability means for providing an available signal when the call detector can detect no calls for elevator service and the door of the elevator car is closed, and said second control means includes means for providing a signal for the availability means indicating that the car door is closed when the car doors are open due to the second control means preventIng the doors from closing by preventing the reset means from initiating the reset signal.
 7. An elevator system, comprising: a building having a plurality of floors, an elevator car mounted for movement in said building to serve at least certain of the floors thereof, said elevator car having a door operable between open and closed positions to enable movement of load between the elevator car and floors of the building, first means for moving the elevator car relative to the floors of said building and to stop the elevator car at selective floors thereof, second means for providing a door open request signal which initiates the opening of the car door in response to predetermined conditions, third means providing a reset signal to initiate the closing of the car door after it has been open a predetermined period of time, fourth means counting the number of door open request signals initiated when the car is at a floor of the building, and providing a signal when a predetermined number of door open requests is reached, and fifth means responsive to the signal provided by said fourth means to prevent the car door from cycling between its open and closed positions.
 8. The elevator system of claim 7 including: call means for registering calls for elevator service from the floors of the building served by the elevator car, car position means providing a car position signal indicative of the closest floor at which the car may make a normal stop when moving and the floor of the car when it is stopped, wherein the second means provides a door open request signal in response to a call for elevator service from the floor of the car position signal, and wherein the fifth means, in response to the signal provided by the fourth means, forces a reset of a call registered from the floor of the car and inhibits a call from the floor provided by said call means from affecting the second means.
 9. The elevator system of claim 8 wherein the call means provides requests for elevator service in both the up and down directions, and the fifth means forces a reset and inhibits the call for service from the floor of the car only for a call having the same service direction as that being served by the elevator car.
 10. The elevator system of claim 9 wherein the fourth means includes first and second counting means for counting door open requests when the car is serving calls for service in the up and down directions, respectively, the fourth means provides first and second signals when the first and second counters reach a predetermined count, respectively, and the fifth means is responsive to said first and second signals to reset and inhibit a call at the floor of the car requesting service in the up and down directions, respectively.
 11. The elevator system of claim 7 including call means for registering calls for elevator service, sixth means which is in a first state when it can detect no calls above or below the position of the car and in a second state when it can, with the fifth means including means responsive to the signal provided by the fourth means when said sixth means is in its first state to prevent the third means from initiating the reset signal for closing the door of the elevator car.
 12. The elevator system of claim 11 including availability means for providing an available signal when there are no calls for elevator service and the door of the elevator car is closed, and said fifth means includes means for providing a signal for the availability means indicating that the car door is closed when the car doors are open due to the fifth means preventing the doors from closing by preventng the third means from initiating the reset signal. 